The critical temperature required for a latex coating to form a strong, continuous film is important in the design and use of these coatings. This temperature is known as the minimum film formation temperature (MFFT).
Presently, an optical method is employed to measure the MFFT. The method involves the observation of the clarity of a cast film on a large metal table. A temperature gradient is applied to the table and the position on the table where the film is judged to be clear is noted. The temperature at that point on the table is determined to be the MFFT value. This technique may provide variable, operator dependent results. Another difficulty with this method is that only optically clear latexes can be tested. Pigments and other additives which are known to alter the MFFT cannot be used using this method. Accordingly a method to objectively measure the film formation temperature of a latex is desirable, especially a method which can also be used with pigmented latices.